NOK/STYK1 interacts with GSK-3β and mediates Ser9 phosphorylation through activated Akt.

NOK (also known as STYK1) has been identified as an oncogene. However, its biochemical and biological activities as a molecular regulator are poorly defined. In the present study, we report that NOK overexpression led to enhanced phosphorylation of GSK-3β at its Ser9 residue via Akt phosphorylation at Thr308. NOK could make complexes with both Akt and GSK-3β. Moreover, the expression levels of NOK, p-Akt(Thr308) and p-GSK-3β(Ser9) were positively correlated in cancerous and non-cancerous breast cell lines. Thus, our data identified a novel functional molecular complex formed by NOK, Akt and GSK-3β that may relay a NOK-directed tumourigenic cascade.